Jim Heyworth worries whether the disks  used  for archiving paper
roll  data  will  last  any  longer  than  the  rolls themselves.
Conservationists have to start with the premise that no medium of
data  recordation (whether  paper,  film,  magnetic  coating,  or
stone) lasts forever, but some last longer than others.  Even  if
floppies ultimately prove to be relatively short-lived, they have
the advantage as  a storage medium over paper rolls that they can
be faithfully and easily replicated, thereby giving them  a whole
new lifespan.

The Conservation Laboratory here  at  the Library of Congress has
done  much research on  paper  and  film,  the  causes  of  their
deterioration, and their probable shelflife.  I  don't  know  how
far  along  they  are  in investigating the  same  questions  for
magnetic or optical disks,  which  are  the  newest  data storage
mediums to  come along.  A  couple of  my  old reel-to-reel tapes
can't  be played because the magnetic coating peels  off  as  the
tape passes over the playback head, while others of  the same age
are  fine.   Quality  of  manufacture  is  one  big  variable  in
shelflife; but who can  do quality control on  the disks he buys?
Storage conditions (temperature, humidity, atmospheric
pollutants,  lighting  and  radiation  factors,  packaging)  also
affect shelflife.  It  may  be  simpler  to  re-copy the  archive
periodically than to try to optimize these factors.  What we need
advice from the conservators on  is  what  the periodicityfor the
re-copying cycle should be.  Does anyone on the list know?

It  is amazing to  me how well most music roll paper manufactured
this century has  lasted.   A  lot  of twentieth-century printing
paper self-destructs in  a matter of years  or decades because of
its high wood pulp and lignin content and  its  high acidity (due
to modern manufacturing techniques).  Most paper of the 15th-18th
century is still in fine condition today, due  to  its  high  rag
content and low lignin and acidity quotient. I think we can count
ourselves lucky that music roll paper has lasted as  long  as  it
has.